ANN ARBOR -- Indiana opened Saturday night by covering Michigan's Senior Day with a wet blanket.

The Hoosiers made their first nine field goals. Most came with relative ease. The Michigan defense was half-a-step slow and overly generous. In a blink, senior Jordan Morgan's final game at Crisler Center began with Michigan trailing 22-12.

It would end as an 84-80 win, U-M's fifth in a row, but not until an old friend showed up.

Early on, the Wolverines' defense was being shredded. Finding open looks against a flat-footed man-to-man defense and beating U-M in transition, Indiana scored easy bucket after easy bucket.

Then that friend arrived. Urged by assistant coaches to make a change, John Beilein switched to a 1-3-1 zone defense trailing 32-25 late in the first half. The move created back-to-back turnovers by Indiana's Will Sheehey and, at long last, the Wolverines offered something resembling a competent defense.

Indiana would finish the first half with 42 points, Michigan's most allowed since being overrun in an 85-67 loss at Iowa eight games ago, but Beilein found something that worked.

Michigan (23-7, 15-3 Big Ten) would go on to use the 1-3-1 for much of the second half.

"It’s the longest (U-M has played zone) in a while," Beilein said. "Similar to probably Florida State this year. We just couldn’t stay in front of them. They’re quick and they have a good plan and given the new way the game is called, it was our only recourse. We couldn’t stay in front of them."

The defense wasn't particularly better in the second half -- Indiana (17-14, 7-11 Big Ten) shot 59.3 percent in the first half and 59.1 percent in the second half -- but the 1-3-1 shifted the game's tempo. The Hoosiers attempted five less shots in the second half and never got quite into the rhythm seen early in the first half.

Michigan outscored Indiana 48-38 in the second half to earn the win.

"We did play man-to-man when we had to, but at the same time, (the 1-3-1) was the only way I thought at that time we’d win the game," Beilein said. "Credit my assistants — they continue to talk me into that, because I hate giving up the 3. They didn’t hit too many."

Mislabeled as a system coach upon arriving at Michigan in 2007, Beilein has steered away from the 1-3-1 over his tenure at U-M. He used the zone as his primary defense as West Virginia coach because it fit his personnel -- typically a shot blocker in the middle, long perimeter defenders who weren't athletic enough for man-to-man along the center and a ball-hawk up top.

Over his years at Michigan, upon recruiting good enough athletes for man-to-man, Beilein all but dropped the 1-3-1. Michigan played man on roughly 95 percent of its possessions last year. It's only popped up on occasion this year.

Brendan F. Quinn covers University of Michigan basketball. Follow him on Twitter for the latest on Wolverines hoops. He can be contacted at bquinn@mlive.com